Cover for a water closet tank



FIG. 1 is a front view of a cover for a water closet tank showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof, the right side being a mirror image of the side shown;

FIG. 4 is a top plan view thereof; and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a cover for a water closet tank, as shown and described. 